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cost of linear actuators

E

Eric Anderson

Jan 1, 1970
0
I have an application where I have to move a 3 lb object in a 3 ft
cubic space. I am not looking at high performance or high accuracy.
It can take as much as 30 seconds to traverse the 3 ft distance and
the accuracy could be no better than 0.020 or 0.050 inch (possibly the
spec could be even looser).

Linear actuators would appear to be the best solution, but I am
finding that they are hundreds or even thousands of dollars. The
product I want to build will have to cost no more than $2,000 for a 3
axis device with controller, overhead and profit.

What is it in a linear actuator that costs so much that you could not
build a low cost version using a threaded rod, servo or stepper motor
and an extruded frame for a lot less?

Does anyone know of a linear actuator that can provide the kind of
performance I am looking for for a couple hundred dollars?
 
J

Jim Stewart

Jan 1, 1970
0
Eric said:
I have an application where I have to move a 3 lb object in a 3 ft
cubic space. I am not looking at high performance or high accuracy.
It can take as much as 30 seconds to traverse the 3 ft distance and
the accuracy could be no better than 0.020 or 0.050 inch (possibly the
spec could be even looser).

Linear actuators would appear to be the best solution, but I am
finding that they are hundreds or even thousands of dollars. The
product I want to build will have to cost no more than $2,000 for a 3
axis device with controller, overhead and profit.

What is it in a linear actuator that costs so much that you could not
build a low cost version using a threaded rod, servo or stepper motor
and an extruded frame for a lot less?

Does anyone know of a linear actuator that can provide the kind of
performance I am looking for for a couple hundred dollars?

You used to be able to buy 1 - 2 foot
actuators cheap. They were used to
position the big K band satellite dishes.
Don't know if they are still available.
 
J

Jon Slaughter

Jan 1, 1970
0
Eric Anderson said:
I have an application where I have to move a 3 lb object in a 3 ft
cubic space. I am not looking at high performance or high accuracy.
It can take as much as 30 seconds to traverse the 3 ft distance and
the accuracy could be no better than 0.020 or 0.050 inch (possibly the
spec could be even looser).

Linear actuators would appear to be the best solution, but I am
finding that they are hundreds or even thousands of dollars. The
product I want to build will have to cost no more than $2,000 for a 3
axis device with controller, overhead and profit.

What is it in a linear actuator that costs so much that you could not
build a low cost version using a threaded rod, servo or stepper motor
and an extruded frame for a lot less?

Does anyone know of a linear actuator that can provide the kind of
performance I am looking for for a couple hundred dollars?

Well, each day the "ego" and "I wanna be a millionaire by tommarrow" taxes
go up. They actually have a college course that preaches to its students
that they have a god given right to make as much money as they can and do as
little work as possible.... I think its called ethics and morality or
something like that. Its a big hit with the medical and law students. The
engineering students are doing well in it.
 
J

Jim Stewart

Jan 1, 1970
0
Jon said:
Well, each day the "ego" and "I wanna be a millionaire by tommarrow" taxes
go up. They actually have a college course that preaches to its students
that they have a god given right to make as much money as they can and do as
little work as possible.... I think its called ethics and morality or
something like that. Its a big hit with the medical and law students. The
engineering students are doing well in it.

That's useful...
 
D

Don Bowey

Jan 1, 1970
0
Well, each day the "ego" and "I wanna be a millionaire by tommarrow" taxes
go up. They actually have a college course that preaches to its students
that they have a god given right to make as much money as they can and do as
little work as possible.... I think its called ethics and morality or
something like that. Its a big hit with the medical and law students. The
engineering students are doing well in it.

I can't see exactly who it is you are attempting to slam with that drivel.
What do you mean by "Its a big hit with the medical and law students. The
engineering students are doing well in it."
 
M

MK

Jan 1, 1970
0
Eric Anderson said:
I have an application where I have to move a 3 lb object in a 3 ft
cubic space. I am not looking at high performance or high accuracy.
It can take as much as 30 seconds to traverse the 3 ft distance and
the accuracy could be no better than 0.020 or 0.050 inch (possibly the
spec could be even looser).

Linear actuators would appear to be the best solution, but I am
finding that they are hundreds or even thousands of dollars. The
product I want to build will have to cost no more than $2,000 for a 3
axis device with controller, overhead and profit.

What is it in a linear actuator that costs so much that you could not
build a low cost version using a threaded rod, servo or stepper motor
and an extruded frame for a lot less?

Does anyone know of a linear actuator that can provide the kind of
performance I am looking for for a couple hundred dollars?

Try www.linak.co.uk who have lots of cheap(ish) actuators. They are used in
furniture and aids for the disabled.

If you are in the US they may have an agent or there will be US suppliers
serving the same market.

Michael Kellett

www.mkesc.co.k
 
P

PeterD

Jan 1, 1970
0
I have an application where I have to move a 3 lb object in a 3 ft
cubic space. I am not looking at high performance or high accuracy.
It can take as much as 30 seconds to traverse the 3 ft distance and
the accuracy could be no better than 0.020 or 0.050 inch (possibly the
spec could be even looser).

Linear actuators would appear to be the best solution, but I am
finding that they are hundreds or even thousands of dollars. The
product I want to build will have to cost no more than $2,000 for a 3
axis device with controller, overhead and profit.

What is it in a linear actuator that costs so much that you could not
build a low cost version using a threaded rod, servo or stepper motor
and an extruded frame for a lot less?

Does anyone know of a linear actuator that can provide the kind of
performance I am looking for for a couple hundred dollars?


Stepper motor/belt drive? Tear in to a couple of old ink jet printers
and see what they do, then multiply the belt size to a length that
meets your needs. You should get the accuracy you need. As to the
weight of the object, you will either need gearing or a large stepper
motor, 3 lb is heavier than a print head...
 
T

Tim Wescott

Jan 1, 1970
0
I have an application where I have to move a 3 lb object in a 3 ft
cubic space. I am not looking at high performance or high accuracy.
It can take as much as 30 seconds to traverse the 3 ft distance and
the accuracy could be no better than 0.020 or 0.050 inch (possibly the
spec could be even looser).

Linear actuators would appear to be the best solution, but I am
finding that they are hundreds or even thousands of dollars. The
product I want to build will have to cost no more than $2,000 for a 3
axis device with controller, overhead and profit.

What is it in a linear actuator that costs so much that you could not
build a low cost version using a threaded rod, servo or stepper motor
and an extruded frame for a lot less?

Does anyone know of a linear actuator that can provide the kind of
performance I am looking for for a couple hundred dollars?

Linear actuators that are sold into industry are designed to work in
anything, bear overload, be easy to engineer around, last forever, and
look good while they're doing it. So of course they're expensive.

If you're going to be building in volume (even modest volume like
100/year) and it's not an aerospace application or a work-anywhere
industrial application then you may do better building your own, or
looking in some of the places others have suggested.

You may also want to look in the Granger's catalog under "jackscrews".
With the right controller and position sensor, these may do what you want.
You may also want to consider hydraulics or pneumatics to get the job done
-- once again you'll have a challenge to find economical parts, but you'll
reduce your motor requirements to one and your actuators will get smaller.

Sounds like a fun project.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html
 
J

Jamie

Jan 1, 1970
0
Eric said:
I have an application where I have to move a 3 lb object in a 3 ft
cubic space. I am not looking at high performance or high accuracy.
It can take as much as 30 seconds to traverse the 3 ft distance and
the accuracy could be no better than 0.020 or 0.050 inch (possibly the
spec could be even looser).

Linear actuators would appear to be the best solution, but I am
finding that they are hundreds or even thousands of dollars. The
product I want to build will have to cost no more than $2,000 for a 3
axis device with controller, overhead and profit.

What is it in a linear actuator that costs so much that you could not
build a low cost version using a threaded rod, servo or stepper motor
and an extruded frame for a lot less?

Does anyone know of a linear actuator that can provide the kind of
performance I am looking for for a couple hundred dollars?
Steel cable loop drive.?

fine Acme threaded traverse screw ?
 
D

default

Jan 1, 1970
0
I have an application where I have to move a 3 lb object in a 3 ft
cubic space. I am not looking at high performance or high accuracy.
It can take as much as 30 seconds to traverse the 3 ft distance and
the accuracy could be no better than 0.020 or 0.050 inch (possibly the
spec could be even looser).

Linear actuators would appear to be the best solution, but I am
finding that they are hundreds or even thousands of dollars. The
product I want to build will have to cost no more than $2,000 for a 3
axis device with controller, overhead and profit.

What is it in a linear actuator that costs so much that you could not
build a low cost version using a threaded rod, servo or stepper motor
and an extruded frame for a lot less?

Does anyone know of a linear actuator that can provide the kind of
performance I am looking for for a couple hundred dollars?

You certainly can build a "lead screw and follower" actuator for a lot
less than thousands - motor and couple of limit switches?

Or motor with a disk and offset pin like a crankshaft to translate
rotary into linear motion.

Don't overlook air cylinders. 3 feet is expensive for a cylinder but
if you can get by with a shorter cylinder with mechanical advantage
they have lots of advantages.

My OM put a satellite dish actuators on his drive way gates. Lot of
hassle running 120 out there and weather proof and in code. All kinds
of problems when something kept the gate from closing or opening
completely (like snow, ice, leaves, debris) and there was the overkill
necessary to make it work. A few air cylinders fixed it with no
hassle - 1/4" OD tubing, the actuators can stay stalled all day long
with nothing to burn out, speed is easy to adjust with a valve,
pressure is also easy to adjust. The only hard part was finding a
pressure switch that would work with the 30 PSI diaphragm pump we had
- the rest of it was hardware store parts.
 
E

Eric Anderson

Jan 1, 1970
0
You certainly can build a "lead screw and follower"actuatorfor a lot
less than thousands - motor and couple of limit switches?

Or motor with a disk and offset pin like a crankshaft to translate
rotary intolinearmotion.

Don't overlook air cylinders. 3 feet is expensive for a cylinder but
if you can get by with a shorter cylinder with mechanical advantage
they have lots of advantages.

My OM put a satellite dish actuators on his drive way gates. Lot of
hassle running 120 out there and weather proof and in code. All kinds
of problems when something kept the gate from closing or opening
completely (like snow, ice, leaves, debris) and there was the overkill
necessary to make it work. A few air cylinders fixed it with no
hassle - 1/4" OD tubing, the actuators can stay stalled all day long
with nothing to burn out, speed is easy to adjust with a valve,
pressure is also easy to adjust. The only hard part was finding a
pressure switch that would work with the 30 PSI diaphragm pump we had
- the rest of it was hardware store parts.
--

- Hide quoted text -

- Show quoted text -

I understand that I could design the components myself. Ultimately I
expect to be building low production quantities of these and was
hoping that a linear actuator/controller combination might exist in
the marketplace so I don't have to redesign the wheel. It will be
required to work in an office environment. I have designed high-speed
line printers and automotive sensors in my career, so I could build
one of these. However, I don't want to find (as I have in the past)
that a simple, low cost solution exists that I could use out-of-the-
box and that is already being built in production quantities.
Ideally, I would like to have 3 linear actuators, 2 of which would be
on an X-Y base and the 3rd that would travel vertically from this X-Y
base (call this the Z axis). I would need to control the three with a
controller that would be programmed from a computer program I would
write for the specific application I have in mind. (I can't divulge
the purpose of this device at this time in case there are patent
issues). I need to be able to represent the position by an icon or
representation of the position using a diagram on the computer
screen. I would have be able to return to previous position (by
storing the X-Y-Z coordinates).
 
D

Don Lancaster

Jan 1, 1970
0
Eric said:
I understand that I could design the components myself. Ultimately I
expect to be building low production quantities of these and was
hoping that a linear actuator/controller combination might exist in
the marketplace so I don't have to redesign the wheel. It will be
required to work in an office environment. I have designed high-speed
line printers and automotive sensors in my career, so I could build
one of these. However, I don't want to find (as I have in the past)
that a simple, low cost solution exists that I could use out-of-the-
box and that is already being built in production quantities.
Ideally, I would like to have 3 linear actuators, 2 of which would be
on an X-Y base and the 3rd that would travel vertically from this X-Y
base (call this the Z axis). I would need to control the three with a
controller that would be programmed from a computer program I would
write for the specific application I have in mind. (I can't divulge
the purpose of this device at this time in case there are patent
issues). I need to be able to represent the position by an icon or
representation of the position using a diagram on the computer
screen. I would have be able to return to previous position (by
storing the X-Y-Z coordinates).
And the problem with a satellite dish leg is...?


--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com
 
D

default

Jan 1, 1970
0
I understand that I could design the components myself. Ultimately I
expect to be building low production quantities of these and was
hoping that a linear actuator/controller combination might exist in
the marketplace so I don't have to redesign the wheel. It will be
required to work in an office environment. I have designed high-speed
line printers and automotive sensors in my career, so I could build
one of these. However, I don't want to find (as I have in the past)
that a simple, low cost solution exists that I could use out-of-the-
box and that is already being built in production quantities.
Ideally, I would like to have 3 linear actuators, 2 of which would be
on an X-Y base and the 3rd that would travel vertically from this X-Y
base (call this the Z axis). I would need to control the three with a
controller that would be programmed from a computer program I would
write for the specific application I have in mind. (I can't divulge
the purpose of this device at this time in case there are patent
issues). I need to be able to represent the position by an icon or
representation of the position using a diagram on the computer
screen. I would have be able to return to previous position (by
storing the X-Y-Z coordinates).

Many years ago there was a demonstration robot that could do that,
although probably couldn't swing three pounds around in its gripper.

It came with a keyboard and you programmed it by laboriously slewing
to the coordinate you wanted one axis at a time, storing that position
then on to the next one. When you played it back the robot would move
in all axis at the same time to get to the coordinate that you put in
memory (one axis at a time). It could also pause for a predetermined
time. It and had an RS232 connector. Forget what it was called. It
was something like $300+ back in the age of DOS.

I only came across it at work and had it do things like dial my phone
and throw switches. No idea why the company bought it. The precision
was excellent - geared stepper motors moving push pull braided steel
cables.

I'm not aware of any ready made, inexpensive, linear positioners that
meet your specs. Maybe some of the robotic or radio control groups?

Lots of hobby interest in modifying the mechanics of scanners to
become X - Y tables - but not 3 foot swings.
 
D

default

Jan 1, 1970
0
And the problem with a satellite dish leg is...?

Do they have feedback or just go to one of two positions and stop?

I bought a surplus one. It is incredibly strong. Has limit switches,
a 24 VDC motor - but no position feedback. Total range of motion is
<20 inches (he mentioned 36" in his original post)

Mine raises and lowers my bed - homebrew " The Amazing! Craftmatic
Adjustable Bed!"
 
E

Eric Anderson

Jan 1, 1970
0
Do they have feedback or just go to one of two positions and stop?

I bought a surplus one. It is incredibly strong. Has limit switches,
a 24 VDC motor - but no position feedback. Total range of motion is
<20 inches (he mentioned 36" in his original post)

Mine raises and lowers my bed - homebrew " The Amazing! Craftmatic
Adjustable Bed!"

You just pointed out an error I made in my original post. I meant to
say the cube was one (1) cubic foot (possibly slightly over that).
That would be just over 1 foot in each of the X, Y and Z directions.
Unfortunately I led everyone to think 3 times what I really needed.
Sorry...

Eganders
 
D

default

Jan 1, 1970
0
You just pointed out an error I made in my original post. I meant to
say the cube was one (1) cubic foot (possibly slightly over that).
That would be just over 1 foot in each of the X, Y and Z directions.
Unfortunately I led everyone to think 3 times what I really needed.
Sorry...

Eganders

I guess I see the problem. A quick search of CNC / XYZ positioners
yields tons of web sites - all seeming to have incredible load
capacities and impressive positioning accuracies - which has to cost.
And since many of them don't give representative prices leads me to
believe they are expensive.

Maybe one technique would be to determine your needs and anticipated
quantities and start phoning or emailing around.

Try posting to a forum - these folks are building that stuff
http://www.cnczone.com/ Lot of pictures showing how others have done
it (but you have to register to get past the thumbnails)

Another search term might be Cartesian robot or gantry robot for a DIY
site. Place I worked at had a laboratory (Cartesian) robot would do
exactly what you want (for about $5K+ but that did include the
computer and software and table)

3 pounds is probably more than any normal scanner positioner can
support directly. They do put Dremel tools on scanners for table top
CNC machines but a Dremel probably only weighs a pound or so.

Satellite dish positioners are probably overkill even if you find one
with feedback. Mine can easily lift 150 pounds takes ~30 seconds to
fully extend/retract - very heavy construction.
 
M

Michael A. Terrell

Jan 1, 1970
0
Jim said:
You used to be able to buy 1 - 2 foot
actuators cheap. They were used to
position the big K band satellite dishes.
Don't know if they are still available.

C band:

http://skyvision.com/store/dishmovers.html


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
R

Robert Latest

Jan 1, 1970
0
Eric said:
What is it in a linear actuator that costs so much that you could not
build a low cost version using a threaded rod, servo or stepper motor
and an extruded frame for a lot less?

Think about it: Who would buy cheap, consumer-grade actuators for
mass-produced items when they can be made even cheaper and better suited to
the task by integrating them into the product itself, like scanners and
copiers?

There simply is no market, so all you can get is heavy-duty,
industrial-grade stuff.

robert
 
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